>Hi netters,
> I wonder if someone may be able to provide a reliable formula to calculate
>the number of DH5-alpha or XL1-Blue based on O.D. measurement. Thanks in
>advance.
>
Hi, there.
Here it goes:
GENERAL:
4-9 x 10^7 cells/ml corresponds to a culture of rec (-) strains at O.D.550
of 0.35-0.60; and to cultures of rec (+) strains at O.D.550 of 0.2-0.4.
For DH1 cells:
4-7 x 10^7 cells/ml corresponds to an O.D.550 of 0.45-0.55.
For x1776 cells:
5-7 x 10^7 cells/microL corresponds to an O.D.550 of 0.2.
The numbers taken from "DNA cloning a practical approach" Vol.I, ed. D.M.Glover.
Good luck,
Nikolai